Wednesday, June 28, 2006

Solutions to Climate Change: Geoengineering

This is the first of a multi-part series on solutions to climate change.

Yesterday's New York Times talks about How to Cool a Planet (Maybe), a review of ways that researchers have proposed we might modify natural processes to diminish the warming caused by greenhouse gases. Among the ideas proposed are mirrors or lenses in space that would block the radiation before it hits the greenhouse gases. These ideas are risky because they don't address the underlying cause.

There are other ideas that would modify ecosystems to increase carbon dioxide uptake:

Another idea was to fertilize the sea with iron, creating vast blooms of plants that would gulp down tons of carbon dioxide and, as the plants died, drag the carbon into the abyss.

This may seem like a very creative idea, and we see less dramatic attempts on a similar line in groups that are planting trees in hopes that they will absorb masses of carbon dioxide and store it until the trees die.

The concept is that vast swaths of ocean that should be very productive aren't. The problem seems to be iron limitation. For ever atom of iron we add, we take hundreds of thousands of carbon dioxide molecules out of the system and store them in biological material. A few tons of iron filings dumped at sea could cause plankton to sequester millions of tons of carbon, and if that carbon sinks below the part of the ocean where oxygen levels can sustain decomposition, the carbon would stay at the bottom of the ocean indefinitely.

The problem with the idea is that plankton die very fast. In ocean experiments and computer simulations of oceans, it's been hard to show any serious draw-down of atmospheric carbon dioxide levels, nor to show that changes persist without constant iron fertilization. As a white paper from MIT puts it (PDF):

iron-fertilization in HNLC ocean regions would not “zero out” global CO2 output under any realistic emissions scenario. Additionally, any atmospheric carbon uptake due to fertilization would be rapidly returned to the atmosphere unless fertilization is sustained for over 50 years.

The paper, based on two author's masters theses, expresses skepticism and caution about the often utopian ideas being proposed for iron fertilization.

But those have a great advantage over strategies for carbon sequestration in stands of trees or in biomass plowed back into soils. At least in principle, the iron concept explains how to keep that carbon from re-entering the atmosphere, while trees rot, forests burn, and soil organic material releases not only carbon dioxide, but methane, an even more potent greenhouse gas.

Beyond the practical objections to current proposals for geoengineering, these ideas face a broader philosophical challenge. As the Times notes:

Geoengineering's advocates say humankind is already vastly altering the global environment and simply needs to do so more intelligently.

That's all well and good, and it's quite true that we need to learn to manage the Earth more effectively. But the suggestion that we're smart and competent enough to restore the equilibrium of the planet with mirrors in space or by dumping iron filings at sea remains tremendously arrogant. No less arrogant than the Promethean hubris which allowed this problem to develop in the first place, but two wrongs do not make a right.

As I hope to show in later posts in the series, there are more practical solutions available to individual people and governmental policy-makers right now, solutions which address the root problem instead of hacking at the exponentially growing consequences of the problem.